Pregnant women, parents and caretakers of young children, all healthcare workers, people between the ages of 6 months and 24 years, and non-elderly adults with underlying medical conditions should be first in line to get the pandemic H1N1 influenza vaccine when it becomes available, an advisory committee for the Centers for Disease Control and Prevention said Wednesday.
That totals about 159 million people in the United States out of a population of more than 300 million. The CDC expects about 120 million doses of the vaccine to be available by the end of October, obviously not enough to cover all of the recommended groups.
But historically, only 20% to 50% of those recommended to receive the seasonal flu vaccine -- about 83% of the population, or about 250 million people -- actually seek it out, so officials are confident there will be plenty of the so-called swine flu vaccine available for those who want it.
But should supplies of the new vaccine be unexpectedly restricted, the committee recommended that a smaller group of about 41 million people receive priority for the vaccine, because they are most likely to suffer adverse effects from infection or to spread the virus: pregnant women, household contacts of children younger than 6, only healthcare workers with direct exposure to infected patients or to the virus, children between 6 months and 4 years of age, and those ages 5 to 18 with underlying risk factors.
The elderly are not included in either group because the H1N1 virus "has largely spared them," Dr. Anne Schuchat, director of the CDC's National Center for Immunization and Respiratory Diseases, said at a news conference.
But the committee strongly urged that the elderly receive the seasonal flu vaccine because that group is most susceptible to complications from more common strains of the flu. Everyone else who is eligible for the seasonal vaccine should also get it, the committee said.
Clinical trials will determine whether the two vaccines can be safely given on the same visit, but experts believe they can. The seasonal vaccine will be available sooner, however, so that may not be an issue.
For now, experts also believe that two doses of the swine flu vaccine will be required for maximum protection.
Schuchat noted that the new vaccine will be tested in pregnant women, but experts believe it will be just as safe as the seasonal vaccine. Only about 15% of pregnant women generally receive the seasonal vaccine, but officials hope for a higher response to the new vaccine because of the enhanced risk in that group.
Pregnant women have four times the normal risk of being hospitalized from complications of the H1N1 virus, and they account for 6% of deaths from H1N1 complications, even though they represent only 1% of the population.
The obese also appear to be at increased risk of complications from swine flu, but it is not yet clear whether that arises from the obesity itself, or from underlying medical conditions such as diabetes and heart disease that often accompany it.
The obese were not included as a separate group with priority for the vaccine, but Schuchat said that the recommendations for people with medical conditions probably cover most of them.